Antipyrine (2,3-dimethyl-1-phenyl-3-pyrazolin-5-one) is a known antipyretic and analgesic. One of its present main uses is to evaluate the rate of drug metabolism in man since the plasma high life of antipyrine is determined by its rate of metabolism.
Recently, Kellermann et al. reported in the New England Journal of Medicine, Vol. 289, No. 18 (Nov. 1, 1973) at page 934 that benzo[a]pyrene hydroxylase inducibility can be associated with risk to bronchogenic carcinoma.
More recently it has been found that there is a direct relationship between the half-life of an individual's plasma antipyrine levels and that individual's genetically controlled level of benzo[a]pyrene hydroxylase induction as measured in isolated lymph-ocytes. See Kellerman et al., Drug Metabolism and Disposition (in press).
The present technique for determining antipyrine plasma levels is based on colorimetric procedures. Use of radioimmunoassay for this purpose would provide an improvement in sensitivity of several magnitudes. Thus it would be possible to obtain more accurate estimates of antipyrine half lives by allowing determinations for this compound over a significantly longer period of time after drug ingestion. In addition lower doses of antipyrine can be used for the test thus decreasing the possible risk of toxic side effects from the drug to the subjects.